/*
 * EAP peer method: EAP-SAKE (RFC 4763)
 * Copyright (c) 2006-2008, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "eap_peer/eap_i.h"
#include "eap_common/eap_sake_common.h"

struct eap_sake_data {
        enum { IDENTITY, CHALLENGE, CONFIRM, SUCCESS, FAILURE } state;
        u8 root_secret_a[EAP_SAKE_ROOT_SECRET_LEN];
        u8 root_secret_b[EAP_SAKE_ROOT_SECRET_LEN];
        u8 rand_s[EAP_SAKE_RAND_LEN];
        u8 rand_p[EAP_SAKE_RAND_LEN];
        struct {
                u8 auth[EAP_SAKE_TEK_AUTH_LEN];
                u8 cipher[EAP_SAKE_TEK_CIPHER_LEN];
        } tek;
        u8 msk[EAP_MSK_LEN];
        u8 emsk[EAP_EMSK_LEN];
        u8 session_id;
        int session_id_set;
        u8 *peerid;
        size_t peerid_len;
        u8 *serverid;
        size_t serverid_len;
};


static const char * eap_sake_state_txt(int state)
{
        switch (state) {
        case IDENTITY:
                return "IDENTITY";
        case CHALLENGE:
                return "CHALLENGE";
        case CONFIRM:
                return "CONFIRM";
        case SUCCESS:
                return "SUCCESS";
        case FAILURE:
                return "FAILURE";
        default:
                return "?";
        }
}


static void eap_sake_state(struct eap_sake_data *data, int state)
{
        wpa_printf(MSG_DEBUG, "EAP-SAKE: %s -> %s",
                   eap_sake_state_txt(data->state),
                   eap_sake_state_txt(state));
        data->state = state;
}


static void eap_sake_deinit(struct eap_sm *sm, void *priv);


static void * eap_sake_init(struct eap_sm *sm)
{
        struct eap_sake_data *data;
        const u8 *identity, *password;
        size_t identity_len, password_len;

        password = eap_get_config_password(sm, &password_len);
        if (!password || password_len != 2 * EAP_SAKE_ROOT_SECRET_LEN) {
                wpa_printf(MSG_INFO, "EAP-SAKE: No key of correct length "
                           "configured");
                return NULL;
        }

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;
        data->state = IDENTITY;

        identity = eap_get_config_identity(sm, &identity_len);
        if (identity) {
                data->peerid = os_malloc(identity_len);
                if (data->peerid == NULL) {
                        eap_sake_deinit(sm, data);
                        return NULL;
                }
                os_memcpy(data->peerid, identity, identity_len);
                data->peerid_len = identity_len;
        }

        os_memcpy(data->root_secret_a, password, EAP_SAKE_ROOT_SECRET_LEN);
        os_memcpy(data->root_secret_b,
                  password + EAP_SAKE_ROOT_SECRET_LEN,
                  EAP_SAKE_ROOT_SECRET_LEN);

        return data;
}


static void eap_sake_deinit(struct eap_sm *sm, void *priv)
{
        struct eap_sake_data *data = priv;
        os_free(data->serverid);
        os_free(data->peerid);
        os_free(data);
}


static struct wpabuf * eap_sake_build_msg(struct eap_sake_data *data,
                                          int id, size_t length, u8 subtype)
{
        struct eap_sake_hdr *sake;
        struct wpabuf *msg;
        size_t plen;

        plen = length + sizeof(struct eap_sake_hdr);

        msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_SAKE, plen,
                            EAP_CODE_RESPONSE, id);
        if (msg == NULL) {
                wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to allocate memory "
                           "request");
                return NULL;
        }

        sake = wpabuf_put(msg, sizeof(*sake));
        sake->version = EAP_SAKE_VERSION;
        sake->session_id = data->session_id;
        sake->subtype = subtype;

        return msg;
}


static struct wpabuf * eap_sake_process_identity(struct eap_sm *sm,
                                                 struct eap_sake_data *data,
                                                 struct eap_method_ret *ret,
                                                 const struct wpabuf *reqData,
                                                 const u8 *payload,
                                                 size_t payload_len)
{
        struct eap_sake_parse_attr attr;
        struct wpabuf *resp;

        if (data->state != IDENTITY) {
                ret->ignore = TRUE;
                return NULL;
        }

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Request/Identity");

        if (eap_sake_parse_attributes(payload, payload_len, &attr))
                return NULL;

        if (!attr.perm_id_req && !attr.any_id_req) {
                wpa_printf(MSG_INFO, "EAP-SAKE: No AT_PERM_ID_REQ or "
                           "AT_ANY_ID_REQ in Request/Identity");
                return NULL;
        }

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending Response/Identity");

        resp = eap_sake_build_msg(data, eap_get_id(reqData),
                                  2 + data->peerid_len,
                                  EAP_SAKE_SUBTYPE_IDENTITY);
        if (resp == NULL)
                return NULL;

        wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_PEERID");
        eap_sake_add_attr(resp, EAP_SAKE_AT_PEERID,
                          data->peerid, data->peerid_len);

        eap_sake_state(data, CHALLENGE);

        return resp;
}


static struct wpabuf * eap_sake_process_challenge(struct eap_sm *sm,
                                                  struct eap_sake_data *data,
                                                  struct eap_method_ret *ret,
                                                  const struct wpabuf *reqData,
                                                  const u8 *payload,
                                                  size_t payload_len)
{
        struct eap_sake_parse_attr attr;
        struct wpabuf *resp;
        u8 *rpos;
        size_t rlen;

        if (data->state != IDENTITY && data->state != CHALLENGE) {
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Request/Challenge received "
                           "in unexpected state (%d)", data->state);
                ret->ignore = TRUE;
                return NULL;
        }
        if (data->state == IDENTITY)
                eap_sake_state(data, CHALLENGE);

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Request/Challenge");

        if (eap_sake_parse_attributes(payload, payload_len, &attr))
                return NULL;

        if (!attr.rand_s) {
                wpa_printf(MSG_INFO, "EAP-SAKE: Request/Challenge did not "
                           "include AT_RAND_S");
                return NULL;
        }

        os_memcpy(data->rand_s, attr.rand_s, EAP_SAKE_RAND_LEN);
        wpa_hexdump(MSG_MSGDUMP, "EAP-SAKE: RAND_S (server rand)",
                    data->rand_s, EAP_SAKE_RAND_LEN);

        if (os_get_random(data->rand_p, EAP_SAKE_RAND_LEN)) {
                wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to get random data");
                return NULL;
        }
        wpa_hexdump(MSG_MSGDUMP, "EAP-SAKE: RAND_P (peer rand)",
                    data->rand_p, EAP_SAKE_RAND_LEN);

        os_free(data->serverid);
        data->serverid = NULL;
        data->serverid_len = 0;
        if (attr.serverid) {
                wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-SAKE: SERVERID",
                                  attr.serverid, attr.serverid_len);
                data->serverid = os_malloc(attr.serverid_len);
                if (data->serverid == NULL)
                        return NULL;
                os_memcpy(data->serverid, attr.serverid, attr.serverid_len);
                data->serverid_len = attr.serverid_len;
        }

        eap_sake_derive_keys(data->root_secret_a, data->root_secret_b,
                             data->rand_s, data->rand_p,
                             (u8 *) &data->tek, data->msk, data->emsk);

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending Response/Challenge");

        rlen = 2 + EAP_SAKE_RAND_LEN + 2 + EAP_SAKE_MIC_LEN;
        if (data->peerid)
                rlen += 2 + data->peerid_len;
        resp = eap_sake_build_msg(data, eap_get_id(reqData), rlen,
                                  EAP_SAKE_SUBTYPE_CHALLENGE);
        if (resp == NULL)
                return NULL;

        wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_RAND_P");
        eap_sake_add_attr(resp, EAP_SAKE_AT_RAND_P,
                          data->rand_p, EAP_SAKE_RAND_LEN);

        if (data->peerid) {
                wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_PEERID");
                eap_sake_add_attr(resp, EAP_SAKE_AT_PEERID,
                                  data->peerid, data->peerid_len);
        }

        wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_MIC_P");
        wpabuf_put_u8(resp, EAP_SAKE_AT_MIC_P);
        wpabuf_put_u8(resp, 2 + EAP_SAKE_MIC_LEN);
        rpos = wpabuf_put(resp, EAP_SAKE_MIC_LEN);
        if (eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
                                 data->serverid, data->serverid_len,
                                 data->peerid, data->peerid_len, 1,
                                 wpabuf_head(resp), wpabuf_len(resp), rpos,
                                 rpos)) {
                wpa_printf(MSG_INFO, "EAP-SAKE: Failed to compute MIC");
                wpabuf_free(resp);
                return NULL;
        }

        eap_sake_state(data, CONFIRM);

        return resp;
}


static struct wpabuf * eap_sake_process_confirm(struct eap_sm *sm,
                                                struct eap_sake_data *data,
                                                struct eap_method_ret *ret,
                                                const struct wpabuf *reqData,
                                                const u8 *payload,
                                                size_t payload_len)
{
        struct eap_sake_parse_attr attr;
        u8 mic_s[EAP_SAKE_MIC_LEN];
        struct wpabuf *resp;
        u8 *rpos;

        if (data->state != CONFIRM) {
                ret->ignore = TRUE;
                return NULL;
        }

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Request/Confirm");

        if (eap_sake_parse_attributes(payload, payload_len, &attr))
                return NULL;

        if (!attr.mic_s) {
                wpa_printf(MSG_INFO, "EAP-SAKE: Request/Confirm did not "
                           "include AT_MIC_S");
                return NULL;
        }

        eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
                             data->serverid, data->serverid_len,
                             data->peerid, data->peerid_len, 0,
                             wpabuf_head(reqData), wpabuf_len(reqData),
                             attr.mic_s, mic_s);
        if (os_memcmp(attr.mic_s, mic_s, EAP_SAKE_MIC_LEN) != 0) {
                wpa_printf(MSG_INFO, "EAP-SAKE: Incorrect AT_MIC_S");
                eap_sake_state(data, FAILURE);
                ret->methodState = METHOD_DONE;
                ret->decision = DECISION_FAIL;
                ret->allowNotifications = FALSE;
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending "
                           "Response/Auth-Reject");
                return eap_sake_build_msg(data, eap_get_id(reqData), 0,
                                          EAP_SAKE_SUBTYPE_AUTH_REJECT);
        }

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending Response/Confirm");

        resp = eap_sake_build_msg(data, eap_get_id(reqData),
                                  2 + EAP_SAKE_MIC_LEN,
                                  EAP_SAKE_SUBTYPE_CONFIRM);
        if (resp == NULL)
                return NULL;

        wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_MIC_P");
        wpabuf_put_u8(resp, EAP_SAKE_AT_MIC_P);
        wpabuf_put_u8(resp, 2 + EAP_SAKE_MIC_LEN);
        rpos = wpabuf_put(resp, EAP_SAKE_MIC_LEN);
        if (eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
                                 data->serverid, data->serverid_len,
                                 data->peerid, data->peerid_len, 1,
                                 wpabuf_head(resp), wpabuf_len(resp), rpos,
                                 rpos)) {
                wpa_printf(MSG_INFO, "EAP-SAKE: Failed to compute MIC");
                wpabuf_free(resp);
                return NULL;
        }

        eap_sake_state(data, SUCCESS);
        ret->methodState = METHOD_DONE;
        ret->decision = DECISION_UNCOND_SUCC;
        ret->allowNotifications = FALSE;

        return resp;
}


static struct wpabuf * eap_sake_process(struct eap_sm *sm, void *priv,
                                        struct eap_method_ret *ret,
                                        const struct wpabuf *reqData)
{
        struct eap_sake_data *data = priv;
        const struct eap_sake_hdr *req;
        struct wpabuf *resp;
        const u8 *pos, *end;
        size_t len;
        u8 subtype, session_id;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_SAKE, reqData, &len);
        if (pos == NULL || len < sizeof(struct eap_sake_hdr)) {
                ret->ignore = TRUE;
                return NULL;
        }

        req = (const struct eap_sake_hdr *) pos;
        end = pos + len;
        subtype = req->subtype;
        session_id = req->session_id;
        pos = (const u8 *) (req + 1);

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Received frame: subtype %d "
                   "session_id %d", subtype, session_id);
        wpa_hexdump(MSG_DEBUG, "EAP-SAKE: Received attributes",
                    pos, end - pos);

        if (data->session_id_set && data->session_id != session_id) {
                wpa_printf(MSG_INFO, "EAP-SAKE: Session ID mismatch (%d,%d)",
                           session_id, data->session_id);
                ret->ignore = TRUE;
                return NULL;
        }
        data->session_id = session_id;
        data->session_id_set = 1;

        ret->ignore = FALSE;
        ret->methodState = METHOD_MAY_CONT;
        ret->decision = DECISION_FAIL;
        ret->allowNotifications = TRUE;

        switch (subtype) {
        case EAP_SAKE_SUBTYPE_IDENTITY:
                resp = eap_sake_process_identity(sm, data, ret, reqData,
                                                 pos, end - pos);
                break;
        case EAP_SAKE_SUBTYPE_CHALLENGE:
                resp = eap_sake_process_challenge(sm, data, ret, reqData,
                                                  pos, end - pos);
                break;
        case EAP_SAKE_SUBTYPE_CONFIRM:
                resp = eap_sake_process_confirm(sm, data, ret, reqData,
                                                pos, end - pos);
                break;
        default:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring message with "
                           "unknown subtype %d", subtype);
                ret->ignore = TRUE;
                return NULL;
        }

        if (ret->methodState == METHOD_DONE)
                ret->allowNotifications = FALSE;

        return resp;
}


static Boolean eap_sake_isKeyAvailable(struct eap_sm *sm, void *priv)
{
        struct eap_sake_data *data = priv;
        return data->state == SUCCESS;
}


static u8 * eap_sake_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_sake_data *data = priv;
        u8 *key;

        if (data->state != SUCCESS)
                return NULL;

        key = os_malloc(EAP_MSK_LEN);
        if (key == NULL)
                return NULL;
        os_memcpy(key, data->msk, EAP_MSK_LEN);
        *len = EAP_MSK_LEN;

        return key;
}


static u8 * eap_sake_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_sake_data *data = priv;
        u8 *key;

        if (data->state != SUCCESS)
                return NULL;

        key = os_malloc(EAP_EMSK_LEN);
        if (key == NULL)
                return NULL;
        os_memcpy(key, data->emsk, EAP_EMSK_LEN);
        *len = EAP_EMSK_LEN;

        return key;
}


int eap_peer_sake_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
                                    EAP_VENDOR_IETF, EAP_TYPE_SAKE, "SAKE");
        if (eap == NULL)
                return -1;

        eap->init = eap_sake_init;
        eap->deinit = eap_sake_deinit;
        eap->process = eap_sake_process;
        eap->isKeyAvailable = eap_sake_isKeyAvailable;
        eap->getKey = eap_sake_getKey;
        eap->get_emsk = eap_sake_get_emsk;

        ret = eap_peer_method_register(eap);
        if (ret)
                eap_peer_method_free(eap);
        return ret;
}
